Iran Is Reported to Test New Centrifuges to Make Atomic Fuel

WASHINGTON — Iran has reportedly begun to deploy a new generation of machinery to produce nuclear fuel, a development bound to intensify a debate in Washington about whether a recent National Intelligence Estimate accurately portrayed Tehran’s progress toward the ability to build a nuclear weapon.

The testing of the new machinery, centrifuges known as IR-2s, was disclosed by European diplomats and American officials and was reported over the past two days in Europe. The development is expected to be included in a report this month by the International Atomic Energy Agency about Iran’s nuclear progress, and whether it has finally resolved questions about activities that have led inspectors to suspect that it may be pursuing weapons.

Centrifuges spin at enormously high speeds to enrich uranium, which can be used to fuel nuclear reactors or, after more processing, nuclear weapons. The IR-2 is an Iranian improvement on a Pakistani design that President Mahmoud Ahmadinejad boasted in an April 2006 speech would quadruple Iran’s enrichment powers.

Reports about the new centrifuges were made just two days after the director of national intelligence, Mike McConnell, told Congress that he had regrets about how the National Intelligence Estimate had been written. He was responding to criticism that the report had left the impression that Iran was no longer seeking a nuclear weapons capability.

The National Intelligence Estimate said that late in 2003 Iran ceased work on a weapons design — but it noted later that Iran was continuing to enrich uranium. Nuclear experts say that building an atomic warhead is less of an engineering challenge than producing the fuel for the weapon.

Mr. McConnell confirmed that in his testimony on Tuesday, saying that weapons design was “probably the least significant part of the program” and that Iran’s refusal to halt uranium enrichment meant that it still posed a potential nuclear threat.

“In retrospect,” he said, “I would do some things differently.”

Iran contends that its nuclear program is for peaceful purposes and that the enrichment will produce fuel for its nuclear plants.

The White House seized on the news about the new centrifuges to argue Thursday that sanctions against Iran should be increased, despite the National Intelligence Estimate’s findings. Gordon D. Johndroe, the spokesman for the National Security Council, said that “if the reports are true, Iran is ramping up its enrichment activities, and this is just a demonstration that they continue to ignore the U.N. Security Council.”

He added that “the recent N.I.E. indicated that enrichment activity could be used for nuclear weapons purposes, and the international community is united that Iran cannot have a nuclear weapon.”

White House officials and outside experts have said that the intelligence estimate took the pressure off Iran. Indeed, the estimate won praise from many experts, who said that previous assessments had overstated the threat from Iran. But for others the disclosure of the new centrifuges suggested the need to keep up the pressure.

“The key question is whether this would speed up the day when they could have a break out capability — the ability to make a small arsenal,” said Gary Samore, the director of studies and a vice president at the Council on Foreign Relations and an expert on the Iranian program. Mr. Samore said the National Intelligence Estimate had played to the interests of Russia and China, which “didn’t want their core economic and political connections to Iran to be threatened.”

“This gave them the pretext” to water down the sanctions, he said.

The new centrifuges have begun to be installed at Iran’s main enrichment complex at Natanz, the officials said. But European news reports on Thursday said no uranium had been fed into the machines.

In an interview, a senior European nuclear official who monitors the Iranian program said the IR-2 was “more ingenious” than its predecessor, an unreliable machine called the P-1, with the “P” reflecting its Pakistani origins. The official insisted on anonymity because of the political delicacy of the issue.

A report released Thursday by the Institute for Science and International Security, a private group in Washington that tracks nuclear proliferation, said the Iranian-made machine was designed to be efficient and reliable.

The report said that if Iran could build 1,200 centrifuges of the new design, it could produce enough weapons-grade uranium for a bomb in one year. Iran would need 3,000 of the current generation of machines to get the equivalent output. It has built that many, experts say, but has had difficulty keeping them running.

At the core of the new centrifuge design is a thin, tubelike rotor made of carbon fibers rather than maraging steel, a variety with great strength, the institute’s report said. Iran has had difficulty making or buying strong maraging steel, largely because the West has stopped shipments headed to the country.

But the report suggested that Iran would need to buy other materials from foreign suppliers — which gives the Untied States and its allies a chance to disrupt the supply chain. It is not clear whether Iran has enough parts to make the new machines in large quantities.

The existence of the IR-2s began to come to light last month after Tehran let senior International Atomic Energy Agency officials visit a complex for the machine’s development.

A version of this article appears in print on , on Page A10 of the New York edition with the headline: Iran Is Reported to Test New Centrifuges to Make Atomic Fuel. Order Reprints|Today's Paper|Subscribe